Inertia-operated switch



May 13, 1952 w.vE. NORDMARK Erm. `2,5196.-,-4257 INERTIA-OPERATED SWITCH Filed OCT.. 26, 1951 (nw KWK .Vl/ll III lll t l i i INVENTORS Walr E. Wordmark Jafeph A.,Millez f Norman C. Poel m @ada-@C16 ATTURNEY Patented May 13, 1952 UNITED STATES PATENT OFFICE INERTIA-OPERATED SWITCH Application October 26, 1951, Serial No. 253,246`

(Cl. ZOO- 52) 16 Claims. l

The present invention relates to an inertiaoperated switch for interrupting an electric circuit.

n The primary object of the invention is to provide an inertia-operated switch adapted for installation on a vehicle, whereby upon sudden deceleration of the vehicle an electric circuit is automatically interrupted for effecting any of several results of a precautionary r corrective nature. Such results may include, for example, the desirable interruption of the ignition circuit oi a motor vehicle in the event of a crash thus to minimize the hazard oi nre, or the activation oi certain signal devices, or the operation of certain safety devices such as shoulder harness reels whereby airplane pilots may be secured in their seats and thus prevented from being suddenly thrown forward in the event oi a crash or during certain maneuvers, or the detonation of an explosive char-ge to destroy mechanisms of a secret nature in cases of accidents involving vehicles on which such mechanisms are installed. The foregoing examples are merely illustrative oi the uses to which the invention may be put and the invention is applicable in any situation where an inertia-operated switch is desired, the new switch being eiilcient in operation, multidirectionally operable to the extent desired, sturdy and relatively simple in construction and reasonably economical in manufacture.

illustrative embodiments of the invention are shown in the accompanying drawing, wherein:

Figure 1 is a central, vertical, longitudinal sectional view through the new switch Figure 2 is a horizontal sectional View thereof taken on line 2-2 of Figure 1; and

Figure 3 is a fragmentary sectional view illustrating a slightly modied form oi the device.

Referring now in detail to this drawing, the new inertia-operated switch illustrated in Figures l and 2, is housed within a generally cylindrical casing Is which as here shown has a closed bottom and an open, externally threaded top. The internal wall oi the casing Ii) is stepped so as to form cylindrical sections separated by a lower shoulder and an upper shoulder I2, the lowermost of the three sections thus formed having the smallest diameter and the uppermost section having the greatest diameter of the three. The casing is desirably made of aluminum.

A lower insulation member or ring I3 is supported on the lower shoulder of the casing, and a similar upper insulation member or ring I4 is supported on the upper shoulder I2 of the casing. These horizontally disposed, vertically spaced insulation rings are preferably made of a hard ber, and are provided with vertically aligned, centrally located, circular openings therethrough designated I5 in the lower ring and IS in the upper ring. The lower ring I3 has an upwardly extending circular rim Il surrounding the upper end of the central opening through said ring I3.

An annular contact member I8 is mounted in the central opening I5 of the lower insulation ring I3 and is provided with a vertically extending, centrally located, circular opening I9 therethrough. The outer part of the circular upper surface of the contact member I8 is flush with the circular upper surface of the rimv |'I on the ring I3, while the inner part of the contact members upper surface is downwardly convergent.

A contact pendulum generally-designated is disposed in the casing and hasa circular head 2| supported by the lower insulation ring I3, a stem 22 depending through the central opening I9 in the contact member I8, and an inertiaresponsive weight 23 at the lower end of the stem 22, below the ring I3. The lower or under surface of the pendulum head 2| is downwardly con- I vergent in its middle region, and the head is normally seated against the upper surface of the Contact member I8. The pendulums head 2| is also provided with a depending peripheral bead 24 which surrounds the upstanding rim I1 on the ring I3 and restrains the pendulums head against lateral movement. The upper surface of the pendulums head 2| is provided with a centrally located concavity 25 therein.

An annular collar 25 is mounted in the central opening IE in the upper insulation ring I4. The upper portion 21 of the collar 23 is internally screw-threaded to receive an adjustment screw 2S, whereas the lower portion of the collar 26 has a centrally located, Vertical slide bearing or barrel 29 in which is vertically slidably disposed a plunger h This plunger 3!) has a well 3| therein opening at the top of the plunger, and the bottom of the plunger is closed and converges downwardly to a rounded tip 32. A helical compression spring 33is disposed within the well 3| of the plunger, and bears at its upper end against the bottom of the adjustment screw 28 and at its lower end against the closed bottom of the plunger 3B. It will be seen that the spring 33 urges the plunger downwardly so that its tip 32 bears against the head 2| of the pendulum 20 in the approximate center of said heads concavity 25, and that the amount of downward pressure thus exerted by the spring may be adjusted by turning the adjustment screw 28.

The casing is provided with a cap 34 threaded on the upper end thereof and provided with a central opening 35 therethrough, through which opening the lead-wires 36, 31 of an electric circuit are introduced into the casing. The lead-wire 3S is connected to the collar 2E in the upper insulation ring I4. The lead-wire 3'! extends through a slot 38 in one side of the upper ring I4, thence through a slot 39 in one side of the lower ring I3, and is connected to a lead-screw 40 which is threaded laterally through the ring I3 and into the annular contact member I8. As shown in the modified form of the invention illustrated in Figure 3 the lead-screw 401 extends well into the contact members central opening I9, for a purpose hereinafter described.

Operation The inertia-operated switch is mounted in a vehicle (or other movable object) in the position illustrated, i. e. with the pendulum depending vertically. The electric circuit to be interrupted by force of inertia, as upon impact of the vehicle with an external object, is normally completed through the lead-wire 36, collar 26, plunger 30, contact pendulum 20, annular contact member I8, lead-screw 40, and lead-wire 31, all of which parts are made of an electrically conductive material such as brass or copper and all of which are insulated from the casing and its cover. The seated contact of the contact pendulum 20 on the annular contact member I 8 is normally maintained by the downward pressure of spring 33 on plunger 30.

The pendulum inertia-responsive weight 23 is, as shown in Figures 1 and 2, operable multidirectionally through 360 degrees, that is, it is free to move in any lateral direction as indicated by the small arrows of Figure 2. When so moved, the depending peripheral bead 24 on the pendulums head 2| engages the upper surface of the insulation ring I3 which serves as a fulcrum about which the pendulum rotates to unseat the pendulums head 2I from the annular contact member I8 as indicated in dotted lines in Figure l. The contact between these two members is thus broken and the electric circuit above described is thus interrupted. Such interruption of the circuit may of itself effect the desired result, or it may operate through a relay to effect such result.

In some instances it may be found desirable to prevent the operation of the device in one or more directions of impact and this may be accomplished by limiting the multidirectional movement of the pendulum to less than 360 degrees. In Figure 3 this has been accomplished by simply substituting a longer lead-screw 401 for the lead-screw 40, which lead-screw 401 would serve to prevent movement of the pendulum to the right as viewed in Figure 3 and thus accomplish the desired end.

It will thus be seen that the invention provides a relatively simple but highly efficient inertia-operable switch, and while but two specic embodiments of the invention have been herein shown and described it will be understood that numerous details may be altered or omitted without departing from the spirit of the invention as the same is defined by the following claims.

We claim:

l. In an inertia-operated switch for interrupting an electric circuit: an insulation member; a contact member mounted in said insulation member and having a vertically extending opening therethrough; a contact pendulum having a head normally seated against the upper surface of said contact member and having a stem depending through the opening in said contact member and provided at its lower end with an inertia-responsive weight whereby said contact pendulum is movable so that the peripheral edge of its head bears against the upper surface of said insulation member to serve as a fulcrum about which the pendulum may rotate to unseat the head thereof from the contact member and thus break the contact between the contact pendulum and the contact member to interrupt an electric circuit therethrough.

2. In an inertia-operated switch for interrupting an electric circuit: an insulation member; an annular contact member mounted in said insulation member and having a circular upper surface and a vertically extending opening therethrough; a contact pendulum having a head normally seated against the circular upper surface of said contact member and having a stem depending through the opening in said contact member and provided at its lower end with an inertia-responsive weight whereby said contact pendulum is movable so that the peripheral edge of its head bears against the upper surface of said insulation member to serve as a fulcrum about which the pendulum may rotate to unseat the head thereof from the annular contact member and thus break the contact between the contact pendulum and the contact member to interrupt an electric circuit therethrough.

3. In an inertia-operated switch for interrupting an electric circuit: an insulation member; an annular contact member mounted in said insulation member and having a circular upper surface and a vertically extending opening therethrough; a Contact pendulum having a circular head of greater diameter than the annular contact member normally seated against the circular upper surface of said contact member and having a stem depending through the opening in said contact member and provided at its lower end with an inertia-responsive weight whereby said contact pendulum is movable so that the peripheral 4edge of its head bears against the upper surface of said insulation member to serve as a fulcrum about which the pendulum may rotate to unseat the head thereof from the annular contact member and thus break the contact between the contact pendulum and the contact member to interrupt an electric circuit therethrough.

4. In an intertia-operated switch for interrupting an electric circuit: an insulation member; an annular contact member mounted in said insulation member and having a circular upper surface and a vertically extending opening therethrough; a contact pendulum having a circular head of greater diameter than the annular contact member normally seated against the circular upper surface of said contact member and having a stem depending through the opening in said contact member and provided at its lower end with an inertia-responsive weight whereby said contact pendulum is movable :nultidirectionally so that the peripheral edge of its head bears against the upper surface of said insulation member to serve as a fulcrum about which the pendulum may rotate to unseat the head thereof from the annular contact member and thus break the contact between the contact pendulum and the contact member to interrupt an electric circuit therethrough.

5. In an inertia-operated switch for interruptagainst the upper surface of said insulation member to serve as a fulcrum about which the pendulumy may rotate to unseat the head thereof .from the annular contact member and thus break the contact between the contact pendulum and the contact member to interrupt an electric circuit therethrough.

6. In aninertia-operated switch for interrupting an electric circuit: an insulation member; an annular contact member mounted in said insulation member and having a circular upper surface and a vertically extending opening therethrough; a contact pendulum having a circular head of greater diameter than the annular contact member normally seated against the circular upper surface ci said contact member and having a stem depending through the opening in said contact member and provided at its lower end with an inertia-responsive weight whereby said contact pendulum is movable multidirectionally so that the peripheral edge of its head bears against the upper surface of said insulation member to serve as a fulcrum about which the pendulum may rotate to unseat the head thereof from the annular contact member and thus break the contact between the contact pendulum and the contact member to interrupt an electric circuit therethrough; and stop means for preventing movement of the pendulum in one direction for limiting the multidirectional movement thereoffto less than 360 degrees.

7. In an inertia-operated switch for interrupting an electric circuit: an insulation member havinga vertically extending annular opening therethrough and provided with an upstanding circular rim surrounding the upper end of said opening; an annular contact member mounted in the openingin said insulation member and having a circular upper surface and a vertically extending opening therethrough; a contact pendulum having a circular head of greater diameter than said rim and provided with a depending peripheral bead surrounding said rim, said head being normally seated against the circular upper surface of said contact member and restrained against lateral movement by the engagement of saidbead with said rime the pendulum being also provided with a stem depending from said head through the opening in said contact member and provided at its lower end with an inertia-responsive weight whereby said contact pendulum is movable so that the depending bead en said head bears against the upper surface of said insulation member to serve as a fulcrum about which the pendulum may rotate to unseat the head thereof from the annular contact member and thus break the Contact between the contact pendulum and the contact member to interrupt an electric circuit therethrough.

8. In an inertia-operated switch for interrupting an electric circuit: an insulation member having a vertically extending annular opening therethrough and provided with an upstanding circular rim surrounding the upper end of said opening; an annular contact member mounted in the opening in said insulation member and having a circular downwardly convergent upper surface and a vertically extending opening therethrough; a contact pendulum having a circular head of greater diameter than said rim and provided with a depending peripheral bead surrounding said rim, said head having a downwardly convergent lower surface and being normally seated against the circular upper surface of said contact member and restrained against lateral movement by the engagement of said bead with said rim, the pendulum being also provided with a stem. depending from said head through the opening in said contact member and provided at its lower end with an inertia-responsive weight whereby said contact pendulum is movable so that the depending bead on said head bears against the upper surface of said insulation member to serve as a ulcrum about which the pendulum may rotate to unseat the head thereoi` from the annular contact member and thus break the contact between the contact pendulum and the contact member to interrupt an electric circuit therethrough.

9. In an inertia-operated switch for interrupting an electric circuit: an insulation member; a contact member mounted in said insulation member and having a vertically extending opening therethrough; a contact pendulum having a head seated against the upper surface of said contact member and having a stem depending through the opening in said contact member and provided at its lower end with an inertiaresponsive weight whereby said contact pendulum is movable se that the peripheral edge of its head bears against the upper surface oi' said insulation member to serve as a fulcrum about which the pendulum may rotate to unseat the head thereof from the contact member and thus break the Contact between the contact pendulum and the contact member to interrupt an electric circuit therethrough; and spring means bearing against the upper surface of the pendulums head for normally pressing said head into seated engagement with the upper surface of said contact member.

10. In an inertia-operated switch for interrupting an electric circuit: an insulation inember having a vertically extending annular opening therethrough and provided with an upstanding circular rim surrounding the upper end of said opening; an annular contact member mounted in the opening in said insulation member and having a circular downwardly convergent upper surface and a vertically extending opening therethrough; a Contact pendulum having a circular head of greater diameter than said rim and provided with a depending peripheral bead surrounding said rim, said head having a downwardly convergent lower surface and being seated against the circular upper surface of said contact member and restrained against lateral movement by the engagement of said bead with said rim, the pendulum being also provided with a stem depending from said head through the opening in said contact member and provided at its lower end with an inertia-responsive Weight whereby said contact pendulum is movable so that the depending bead on said head bears against the upper surface of said insulation member to serve as a fulcrum about which the pendulum may rotate to unseat the head thereof from the annular contact member and thus break the the contact between the contact pendulum and the contact member to interrupt en electric circuit therethrough; and spring means bearing against the upper surface of the pendulums head for normally pressing said head into seated engagement with the upper surface of said contact member.

l1. In an inertia-operated switch for interrupting an electric circuit: a casing; a pair of insulation members mounted in the casing in vertically spaced relation, the lower insulation member having a vertically extending opening therethrough; a contact member mounted in the lower insulation members opening and having a vertically extending opening therethrough; a contact pendulum having a head adapted to seat against the upper surface of said contact member and having a stem depending through the opening in said contact member and provided at its lower end with an inertia-responsive weight whereby said contact pendulum is movable so that the peripheral edge of its head bears against the upper surface of the lower insulation member to serve as a fulcrum about which the pendulum may rotate to unseat the head thereof from the contact member and thus break the contact between the contact pendulum and the contact member to interrupt an electric circuit therethrough; and spring means interposed between the upper insulation member and the upper surface of the pendulum for normally pressing said head into seated engagement with the upper surface of said contact member.

12. In an inertia-operated switch yfor interrupting an electric circuit: a casing; a pair of insulation members mounted in the casing in vertically spaced relation, the lower insulation member having a vertically extending opening therethrough; a contact member mounted in the lower insulation members opening and having a vertically extending opening therethrough; a contact pendulum having a head adapted to seat against the upper surface of said contact member and having a stem depending through the opening in said contact member and provided at its lower end with an inertia-responsive weight whereby said contact pendulum is movable so that the peripheral edge of its head bears against the upper surface of the lower insulation member to serve as a fulcrum about which the pendulum may rotate to unseat the head thereof from the contact member and thus break the contact between the Contact pendulum and the contact member to interrupt an electric circuit therethrough; a plunger vertically slidably mounted in the upper insulation member and bearing at its lower extremity against the upper surface of said contact pendulums head; and spring means interposed between the upper insulation member and the plunger for normally urging said plunger downwardly.

13. In an inertia-operated switch for interrupting an electric circuit: a casing; a pair of insulation members mounted in the casing in vertically spaced relation, the lower insulation member having a vertically extending opening therethrough; a contact member mounted in the lower insulation members opening and having a vertically extending opening therethrough; a contact pendulum having a head adapted to seat against the upper surface of said contact member and having a stem depending through the opening in said contact member and provided at its lower-end with an inertia-responsive weight.

whereby said contact pendulum is movable so that the peripheral edge of its head bears against the upper surface of the lower insulation member to serve as a fulcrum about which the pendulum may rotate to unseat the head thereof from the contact member and thus break the contact between the Contact pendulum and the contact member to interrupt an electric circuit therethrough; a plunger vertically slidably mounted in the upper insulation member and bearing at its lower extremity against the upper surface of said contact pendulums head; and spring means interposed between the upper insulation member and the plunger for normally urging said plunger downwardly, the upper surface of said pendulums head having a concavity therein and the lower extremity of said plunger having a tip bearing in the approximate center of said concavity.

14. In an inertia-operated switch for interrupting an electric circuit: a casing; a pair of insulation members mounted in the casing in vertically spaced relation, said members having vertically aligned openings therethrough; a contact member mounted in the lower insulation members opening and having a vertically extending opening therethrough; a contact pendulum having a head adapted to seat against the upper surface of said contact member and having a stem depending through the opening in said contact member and provided at its lower end with an inertia-responsive weight whereby said contact pendulum is movable so that the peripheral edge of its head bears against the upper surface of the lower insulation member to serve as a fulcrum about which the pendulum may rotate to unseat the head thereof from the contact member and thus break the contact between the contact pendulum and the contact member to interrupt an electric circuit therethrough; a collar mounted in the opening in the upper insulation member and having an opening therethrough the upper portion of which is internal threaded and the lower portion of which constitutes a vertically extending barrel; a plunger vertically slidably disposed in said barrel and having a well in its upper portion and a closed bottom bearing against the upper surface of said contact pendulums head; an adjustment screw threaded in the upper threaded portion of said collars opening; and a spring interposed between said screw and the bottom of the plungers well for normally urging said plunger downwardly to complete an electric circuit through the collar, the plunger, the pendulum and the contact member.

15.1n an inertia-operated switch for interrupting an electric circuit: an insulation member; an annular contact member mounted in said insulation member and having a circular upper surface and a vertically extending opening therethrough; a contact pendulum having a circular head of greater diameter than the annular contact member normally seated against the circular upper surface of said contact member and having a stem depending through the opening in said contact member and provided at its lower end with an inertia-responsive weight whereby said contact pendulum is movable so that the peripheral edge of its head bears against the upper surface of said insulation member to serve as a fulcrum about which the pendulum may rotate to unseat the head thereof from the annular contact member and thus break the contact between the contact pendulum and the contact member to interrupt an electric circuit therethrough; and a lead-screw threaded laterally through the insulation member and into said annular Contact member.

16. In an inertia-operated switch for interrupting an electric circuit: an insulation member; an annular contact member mounted in said insulation member and having a circular upper surface and a vertically extending opening therethrough; a contact pendulum having a circular head of greater diameter than the annular contact member normally seated against the circular upper surface of said contact member and having a stem depending through the opening in said contact member and provided at its lower end with an inertia-responsive Weight whereby said contact pendulum is movable multidirectionally so that the peripheral edge of its head bears against the upper surface of said insulation member to serve as a fulcrum about which the pendulum may rotate to unseat the head thereof from the annular contact member and thus break the contact between the contact pendulum and the contact member to interrupt an electric circuit therethrough; and a lead-screw threaded laterally through the insulation member and through said annular contact member and extending into the vertically extending open-- ing in said contact member, the inner end of said lead-screw serving as a stop against which the pendulum may abut to limit the multidirectional movement of the pendulum to less than 360 degrees.

WALTER E. NORDMADK.

JOSEPH A. MILLER.

NORMAN C. POEL.

REFERENCE S CYTED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,236,872 Grigsby Apr. 1, 1941 2,264,097 Neeper Nov. 25, 1941 

